Comparative Analysis of Surgical Exposure among Endoscopic Endonasal Approaches to Petrosectomy: An Experimental Study in Cadavers

Objectives Endoscopic endonasal approaches (EEAs) for petrosectomies are evolving to reduce perioperative brain injuries and complications. Surgical terminology, techniques, landmarks, advantages, and limitations of these approaches remain ill defined. We quantitatively analyzed the anatomical relationships and differences between EEA exposures for medial, inferior, and inferomedial petrosectomies. Design This study presents anatomical dissection and quantitative analysis. Setting Cadaveric heads were used for dissection. EEAs were performed using the medial petrosectomy (MP), the inferior petrosectomy (IP), and the inferomedial petrosectomy (IMP) techniques. Participants Six cadaver heads (12 sides, total) were dissected; each technique was performed on four sides. Main Outcomes and Measures Outcomes included the area of exposure, visible distances, angles of attack, and bone resection volume. Results The IMP technique provided a greater area of exposure (p < 0.01) and bone resection volume (p < 0.01) when compared with the MP and IP techniques. The IMP technique had a longer working length of the abducens nerve (cranial nerve [CN] VI) than the MP technique (p < 0.01). The IMP technique demonstrated higher angles of attack to specific neurovascular structures when compared with the MP (midpons [p = 0.04], anterior inferior cerebellar artery [p < 0.01], proximal part of the cisternal CN VI segment [p = 0.02]) and IP (flocculus [p = 0.02] and the proximal [p = 0.02] and distal parts [p = 0.02] of the CN VII/VIII complex) techniques. Conclusion Each of these approaches offers varying degrees of access to the petroclival region, and the surgical approach should be appropriately tailored to the pathology. Overall, the IMP technique provides greater EEA surgical exposure to vital neurovascular structures than the MP and the IP techniques.

Influence of annealing on the functional properties of the NiTi alloy produced by wire arc additive manufacturing

The influence of the annealing temperature on the recoverable strain variation on cooling and heating under a stress of 200 MPa was studied in the NiTi samples produced by wire arc additive manufacturing. The samples including the Ni-rich NiTi layer in the working length were annealed for 10 hours at various temperature from 450 to 600 °C. It is shown that an increase in annealing temperature leads to non-monontonic variation in the recoverable strain. This is caused by an increase in annealing temperature from 450 to 550 °C increases the volume fraction of Ni4Ti3 precipitates. As a result, the volume fraction of the NiTi phase undergoing the martensitic transformation and recoverable strain decrease. An increase in annealing temperature from 550 to 600 °C leads to a dissolving the Ni4Ti3 precipitates and formation of the Ni3Ti2 precipitates that increases the volume fraction of the NiTi phase and the recoverable strain.

Transcarotid access for remote robotic endovascular neurointerventions: a cadaveric proof-of-concept study

OBJECTIVE The purpose of this proof-of-concept study was to demonstrate the setup and feasibility of transcarotid access for remote robotic neurointerventions in a cadaveric model. METHODS The interventional procedures were performed in a fresh-frozen cadaveric model using an endovascular robotic system and a robotic angiography imaging system. A prototype remote, robotic-drive system with an ethernet-based network connectivity and audio-video communication system was used to drive the robotic system remotely. After surgical exposure of the common carotid artery in a cadaveric model, an 8-Fr arterial was inserted and anchored. A telescopic guiding sheath and catheter/microcatheter combination was modified to account for the “workable” length with the CorPath GRX robotic system using transcarotid access. RESULTS To simulate a carotid stenting procedure, a 0.014-inch wire was advanced robotically to the extracranial internal carotid artery. After confirming the wire position and anatomy by angiography, a self-expandable rapid exchange nitinol stent was loaded into the robotic cassette, advanced, and then deployed robotically across the carotid bifurcation. To simulate an endovascular stroke recanalization procedure, a 0.014-inch wire was advanced into the proximal middle cerebral artery with robotic assistance. A modified 2.95-Fr delivery microcatheter (Velocity, Penumbra Inc.) was loaded into the robotic cassette and positioned. After robotic retraction of the wire, it was switched manually to a mechanical thrombectomy device (Solitaire X, Medtronic). The stentriever was then advanced robotically into the end of the microcatheter. After robotic unfolding and short microcatheter retraction, the microcatheter was manually removed and the stent retriever was extracted using robotic assistance. During intravascular navigation, the device position was guided by 2D angiography and confirmed by 3D cone-beam CT angiography. CONCLUSIONS In this proof-of-concept cadaver study, the authors demonstrated the setup and technical feasibility of transcarotid access for remote robot-assisted neurointerventions such as carotid artery stenting and mechanical thrombectomy. Using transcarotid access, catheter length modifications were necessary to achieve “working length” compatibility with the current-generation CorPath GRX robotic system. While further improvements in dedicated robotic solutions for neurointerventions and next-generation thrombectomy devices are necessary, the transcarotid approach provides a direct, relatively rapid access route to the brain for delivering remote stroke treatment.

Study of heat transfer during steam condensation in the tubes of diesel radiator cores

The article contains an assumption about the practicability of using the processes of boiling and condensation of the coolant in the cooling system of a locomotive diesel in order to reduce the energy consumption of fans of the refrigerating chamber. The possibility of using of standard radiator cores of a diesel locomotive with flat tubes as steam condensers is considered. The results of the criterion equation of heat transfer from steam to a flat tube during condensation, obtained by the mathematical model of this process, are estimated. The assessment was carried out by comparison with experimental data. The influence of the initial steam velocity, the corresponding tube diameter, the working length of the tube, the physical properties of steam and condensate is considered. The comparison of the influence of these factors on heat transfer in round and flat tubes of a locomotive radiator core is carried out. The processed results of physical and numerical experiments for both circular and flat tubes are shown in the graphs and regression equations. The advantage of flat tubes over round ones in terms of heat transfer intensity during steam condensation, which can reach 24%, for a standard radiator core of a diesel locomotive was found.

EXAMINATION OF DISINFECTANTS USING AN AUTOMATED SPECTROMETER OPERATING IN THE VISIBLE RANGE OF THE SPECTRUM

The paper highlights a modern spectral device for measuring the optical parameters of solid-state materials in liquid-phase. The development of these devices is promising for optical instrumentation and science in general, since these devices are informative, highly accurate and provide reliable information. In the paper the appearance, block diagram and lighting system of the spectrometer are presented. The spectral dependences of the transmission on the wavelength in the visible range of the spectrum for disinfectants Like, Grand, Aqualite (1% solutions) are obtained. For the analysis of the studied substances, specialized cuvettes with a working length from 0.1 to 0.5 mm and leucosapfir optical pads were used. The cuvettes were 0.05 mm thick. The spectrometer provided measurement of the transmission of disinfectants in the wavelength range of 380–760 nm with an error not worse than ΔТ ≤ 2%.

Adaptation of the single-cone in prepared long oval-shaped canals: a micro-computed tomography study

The present study aimed to evaluate adaptation of the single gutta-percha cone on root canal walls prepared with the two systems, the XP-endo Shaper (XPS; FKG Dentaire, La Chaux-de-Fonds, Switzerland) and ProTaper Next systems (PTN; Dentsply Sirona, Ballaigues, Switzerland) by using micro-computed tomography (micro-CT) technology. Twenty long oval-shaped canals in mandibular incisors were scanned by micro-CT (Skyscan 1172; Bruker microCT, Kontich, Belgium). Two groups were divided into (n = 10) according to the canal preparation protocol: XPS group with an extra 45 s of instrumentation and PTN group. A gutta percha cone, with respect to the protocol used for each group (size 40, .04 taper, XPS and size 40, .06 taper, PTN) was adapted to the canal at the working length of all the samples, and all root canals were filled, using the single-cone technique. The mean values for volume of voids and percentage relative to the mentioned space were correspondingly higher in XPS group than they were PTN group, mean values for volume of voids (3.61 mm3 - 1.92 mm3) and for percentage of voids (39.25% - 23.28%), respectively, significant differences were recorded (p < 0.05) between the two groups (XPS and PTN, Student’s-t test for homogenous variances and Mann–Whitney test). The canals prepared with XPS, in the procedure performed with an extra 45 s of instrumentation, showed a higher volume of voids than those prepared with the PTN system, in obturation of the root canal with the single cone technique.